1. Field of the Invention
The present invention relates to a control apparatus for a hybrid vehicle which is mounted in a hybrid vehicle propulsion driven by jointly using an internal-combustion engine and a motor, and wherein the driving force from at least one of the internal-combustion engine and the motor is transmitted to the driving wheels.
Priority is claimed on Japanese Patent Application No. 2003-192308 and No. 2003-192314, both filed Jul. 4, 2003, the contents of which are incorporated herein by reference.
2. Description of Related Art
Conventionally, for example, in a hybrid vehicle which comprises an internal-combustion engine and a motor as a power source and wherein the driving force from at least one of the internal-combustion engine and the motor is transmitted to the driving wheels for propulsion, a control apparatus for a hybrid vehicle has been well known which calculates the throttle opening for minimizing the fuel consumption of the internal-combustion engine with respect to the rotation frequency of the input shaft of the transmission, and based on this throttle opening and the accelerator operating amount of a driver, allocates the torque required by the power plant (that is, the internal-combustion engine and the motor), to the engine torque required by the internal-combustion engine and to the motor torque required by the motor (for example, refer to Japanese Patent Application Unexamined Publication No. Hei 9-163509).
Incidentally, in the control apparatus for a hybrid vehicle according to an example of the above conventional technique, since the torque that is capable of being output from the motor fluctuates according to the charging state, temperature, and the like, of a power storage unit which transfers electrical energy to and from the motor, for example, there is concern that the torque output from the motor or the power plant (that is, the internal combustion engine and the motor) fluctuates even with the same accelerator operating amount, for example. Hence the driver's intention is not appropriately reflected in the traveling behavior of the vehicle, resulting in a deterioration of drivability. Furthermore, there is concern that a desired torque cannot be output from the motor and the power plant (that is, the internal combustion engine and the motor) simply by setting the torque allocation with respect to an engine torque instruction and a motor torque instruction according to the driver's accelerator operating amount, engine speed, speed of the vehicle (vehicle speed) and the like.
Moreover, for example, there is concern that when shifting from an executing state for fuel cut (F/C) which cancels the fuel supply to the internal-combustion engine during a regenerative operation of motor due to the accelerator operating amount of driver being a value of zero or in the vicinity of zero, to a F/C resetting state which restarts the fuel supply, the torque output from the power plant rapidly fluctuates (that is, increases), so that a change in the traveling behavior occurs which is not expected by the occupants of the vehicle. As a result, the drivability deteriorates.